Tiger and Quartz 2D Extreme

In its excellent review on Tiger, ARS Technica gives details on Quartz 2D Extreme. This Tiger-specific feature allows 2D to be managed by the GPU and not the CPU anymore; and published tests prove that performance can be improved up to 236 fold!
But for an unknown reason, Apple did not activate this function by default...
I you wish to play with this feature, it is possible to force its activation with the application Quartz Debug which is part of Developers Tools.
The result of the activation of Quartz 2D Extreme is really impressive. On a PMG5 Dual 2.5GHz equipped with a GeForce6800, moving quickly a window on the desktop was generating up to 33% of CPU usage dedicated to "WindowServer" process. Once Quartz 2D Extreme is activated, the dedicated CPU usage drops to 13%.
It saves a lot of CPU usage, and will for sure much more appreciated with computers based on less performing processors.
If you have not faced any troubles after your test, you can force Quartz 2D Extreme to be active by default by entering directly in the Terminal the following command line:

sudo defaults write /Library/Preferences/com.apple.windowserver \Quartz2DExtremeEnabled -boolean YES

Your administrator password will be required.
If later on you have problems or artifacts, then you can inactivate this feature by entering the same command line with modifying YES to NO.